Outline

Objective

At the present time only visual analysis is implemented on dacryoscintigraphic images and quantitative assessments are not attained routinely. We applied a simple quantitative method for diagnosis of sac and post-sac obstructions based on the dacryoscintigraphic images.

Methods

48 patients with severe unilateral epiphora were included and contralateral asymptomatic eyes were considered as control. After ocular instillation of 0.1cc isotonic saline containing 4 MBq 99mTcO4, dynamic images were obtained for 20 minutes. Visual interpretation was performed by two blinded nuclear medicine physicians. A Time-Activity Curve (TAC) was generated for each eye and its pattern was divided to plateau type, shallow-down sloping and deep-down sloping. We calculated the excretion ratio (expressed as the percentage of drainaged activity) in the 2nd, 3rd, 5th, 7th, 10th, 15th and 20th min of the study based on the following formula: (the whole ROI count in the 1st min - the whole ROI count in the 2nd, 3rd, 5th, 7th, 10th, 15th or 20th min of the study/ the whole ROI count in the 1st min) x100. Results of the quantitative analysis were compared with the clinical symptoms, visual analysis and TAC pattern.

Results

At the optimal cut-off points for 2nd, 3rd, 5th and 7th min, the sensitivity of prediction of obstruction was 77%, 71%, 64% and 61%, respectively. The correlation between visual interpretation and the pattern of TAC was statistically significant.

Conclusions

In our opinion, the quantitative evaluation of dacryoscintigraphic images would contribute greatly in helping to better interpret the scintigraphic results.